I know there is a forging program for windows but I don't know whats it called I have heard about it I was wondering if anyone knew the name of that program???
Google Sketchup. Sketchup is the best designing program I've come across and you can download components for Halo 3.
Well that is going a little detailed I mean a program that is basically the same this as halo 3 set up but you use a mouse and its a little details not bare bones!!!
There is no PC version of Halo 3's Forge outside of the Bungie Studios. Sketchup is the closest program you'll get for modelling your map in 3D but you will not find a program exactly like Forge and don't get your hopes up for one which allows you to export maps from your PC to the Xbox.
But Google Sketchup takes up way too much time.So I would use it for short maps.Yeah,GoogleSketchup is the best there though.